Soil, water, and climatic classification systems are reviewed as background for the construction of a classification system for earthen aquaculture ponds. The physical and chemical properties of important soil types are also reviewed because of the critical role that the soil plays in earthen pond systems. A pond classification system is constructed using key elements from established climate, water, and soil classification systems, and its use as a management tool is demonstrated. Additional benefits of pond classification are discussed. Functional relationships pertaining to a particular management practice--the application of lime--are examined for seven classes of acid soils. Theoretical and empirical models of pH-percent base saturation relationships are evaluated using data from United States soils. Selected models are partially validated using an independent set of data and incorporated into a lime requirement determination model. A table of lime requirement estimates based on initial soil pH values is calculated for each soil class. Partial validation of the classification system is achieved by ANOVA for the cation exchange capacities of the soils, by fitting the selected pH-percent base saturation models to data from an independent source, and by comparison of the estimated lime requirements with previously published guidelines. Possible reasons for weaknesses in the classification system, the pH-percent base saturation models, or the approach to lime requirement determination are explored, and areas requiring further research are identified. Additional uses and benefits, and further validation and refinement of the classification system are discussed. It is concluded that the proposed classification is a good first approximation that provides a basis for further work. / Graduation date: 1992